The present invention relates to cutting tools and, more particularly, to tools for countersinking, chamfering and deburring holes.
When holes are made by drilling or punching in metal, ceramic or plastic, the holes are often rough at their entrances or exits. Conventionally, drill bits and the like are used as hole finishing tools to remove a small amount of material. Drill bits have the disadvantage that they are not adaptable to finishing small holes. In addition, especially when the holes are larger, tool chatter frequently produces roughness in the material.
A different type of hole finishing tool employs the hole in the material as a pilot hole into which is fitted a pilot piece. An angled cutting edge is guided by the pilot piece to remove a small amount of material at the entrance of the hole. Although the piloted hole finishing tool solves the problem of tool chatter, and consequent roughness of the cut, the pilot piece and cutting blades are relatively large, thus making the piloted hole finishing tool unsuitable for finishing small holes.
An object oft his invention is to provide an improved hole finishing tool for chamfering and deburring holes, particularly holes drilled or punched in metal.
Another object of this invention is to provide a hole finishing tool which offers the advantage of a piloted chamfering tool, but which is useable on large and very small holes alike.
A further object of this invention is to provide a dependable hole finishing tool suited for the manufacturing environment that is simple to use.
A still further object of the invention is to provide a hole finishing tool of simple design and construction that renders it relatively inexpensive to produce and therefore more cost effective to the end user.
Briefly stated, the present invention provides a hole-finishing hole finishing tool which includes a pilot cone within which a quarter round section is free to be displaced in an axial direction. The quarter round section is resiliently biased away from a workpiece. When the tip of the pilot cone is inserted into a hole in a workpiece and force is applied, the quarter round section is displaced forward into contact with the perimeter of the hole, thereby deburring, chamfering or countersinking is performed. The use of a pilot cone stabilizes the cutting element and a quarter round single lip cutting edge permits the tool to be used on small holes.
According to an embodiment of the invention, there is provided a hole finishing tool comprising: a support member, the support member having a shape that is fittable into a hole in a workpiece, a shank, an end of the shank passing through the support member, the end having a cutting element formed or fastened thereon, means for resiliently biasing the shank away from the support member sufficiently to withdraw the cutting element within a contour of the support member, and means for permitting the application of a force to the shank sufficient to extend the cutting element into working contact with a perimeter of the hole.
According to a feature of the invention, there is provided a hole finishing tool comprising: a pilot cone, the pilot cone including a slot passing axially therethrough, a shank, a section of the shank having a peripheral shape fitting through the slot, a cutting element at an extremity of the section, a resilient element axially biasing the shank away from the pilot cone sufficiently to withdraw the cutting element within a contour of the pilot cone, means for permitting the shank to be urged a predetermined distance forward by application of a force thereon, and the predetermined distance being sufficient to extend the cutting element into working contact with a perimeter of a hole in a workpiece.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.